This invention relates to a truck trailer goose neck apparatus and particularly for interconnecting of a low-boy trailer to a truck tractor.
Commercial trucking includes semitrailer systems wherein a truck tractor is releasably coupled to a trailing load carrying trailer for over the road transport of loads. A low-boy trailer is widely used for transport of off-road construction equipment, such as graders, shovels and the like. The low-boy trailer consists of a supporting flat bed structure of a convenient length and width for carrying one or more off-road vehicles. The flat bed is supported at the trailing end by one or more sets of tired wheel supports. The bed structure extends forwardly from the wheel supports and is pivotally supported thereon. The gooseneck apparatus is connected to and supports the free end of the flat bed for over the road movement. Thus, the gooseneck apparatus generally includes a vertical section connected to the forward end of the trailer and a horizontal section which extends forwardly from the vertical section with a releasable pin coupling to the fifth wheel as a cooperating coupling element on the truck tractor. The off-road equipment may be conveniently loaded and unloaded from the trailer bed structure at the forward free end. The gooseneck structure is therefore releasably coupled to the forwarding end of the trailer or the structure may be constructed to form a collapsable ramp structure for loading and unloading of the off-road vehicles. The gooseneck structure is also normally built with hydraulically actuated members within the gooseneck structure for relative movement relative to the bed structure for separation from the trailer bed with the gooseneck in place on the truck tractors. The operator will drive to the loading or the unloading site, sets the brakes on both the truck tractor and the trailer to establish a firm stopping of each unit. The hydraulic system is actuated for repositioning and release of the gooseneck structure from the trailer bed. For example, a collapsable gooseneck structure is shown for creating a loading and unloading ramp is shown in U.S. Pat. No. 3,419,119. Generally the conventional system employs complete disconnection of the gooseneck structure from the trailer bed which permits the lowering of the bed structure to the ground for convenient movement of the off-road vehicles onto and/or from the bed structure. Various systems have been suggested in the patented art and certain systems used for releasable connection of the trailer. For example, detachable gooseneck structures for releasably coupling to the trailer bed are shown in U.S. Pat. Nos. 2,545,584; 2,777,713; 2,822,945; 2,944,834; 2,953,396; 2,967,720; 2,978,128; 3,027,030; 3,215,449; 3,384,390; 3,416,683; 3,419,169; 3,450,417 and 3,498,636. The prior art generally includes various hydraulic systems for repositioning of the gooseneck structure relative to the trailer bed with an interrelated repositioning of the trailer bed during the connection and disconnection.
The truck-trailer units are heavy and massive structures, and the truck tractor and the trailer is provided with an individual braking unit. The braking units are operable during over road movement for stopping or slowing of the movement of the assembly. The individual brakes are also used to or set to hold the separate units immovable when stopped and the trailer is to be separated. This becomes particularly significant of course if the units are parked upon an inclined surface or ground. In the separation of the truck tractor from the trailer, it is therefore desirable and often necessary to have the brake units set. However, with the conventional gooseneck connections some relative movement between the trailer and truck tractor is often created tending to move the trailer relative to the truck tractor. If the truck and the trailer brakes are set, relatively skidding movement between the truck tractor and the trailer must occur, placing relatively heavy loads on the assembly. Such skidding makes separation difficult if the assembly is on any significant grade or the ground is soft. Off-road vehicles may require unloading at a building site where the ground is reasonably soft and a hard supporting surface is not conveniently available. Thus, creating the necessary relative movement between the trailer and truck tractor may require exceedingly high forces and may even create excessive if not damaging loading on the separating apparatus. Although hydraulic power systems may be constructed of a sufficient strength and force to affect separation where required, the complexity and cost is relatively substantial.